Session-10-Present Perfect simple Vs, continous Tense

We prefer the Present Perfect Simple for permanent situations or for longer time periods. We prefer the Present Perfect Continuous for temporary situations or for shorter time periods. But it is often possible to use either the Present Perfect Continuous (to put emphasis on the length of time) or the Present Perfect Simple.We often make questions which begin How long...? with a Present Perfect Continuous verb. 

How long have you been learning English ?

How long has she been watching T.V?